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Bluetooth Speaker - DIY

About: An electronics enthusiast who just wants to share his idea to the rest of the world.
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I just found that I had a couple of speakers lying around and I wanted to put it good use. So, I decided to make a Bluetooth speaker. This is my first instructable, Hope you guys find this useful.

Step 1: Components Required:

Speakers

Audio Amplifier (depending upon speakers)

Bluetooth Audio Receiver Module

Male and Female USB connectors (if powering through a laptop or other devices)

Male and Female audio jack (3.5mm)

Connecting Wires

Soldering Iron and lead

18650 Li-Ion Batteries (If you want a portable one )

DC-DC Booster

TP4056 Charging Module

Step 2: Speakers:

Now, you can choose any type of speakers. You can buy these in any hardware stores or it can be salvaged from other devices. I got mine from an old PC. But the bottom line is, any speaker that works is fine.

All speaker have their ratings printed at the back. These values will be important for us to choose the right type of amplifier. For example, mine reads ' 5 W and 8 ohms'. These power and output impedance are very important while choosing an amplifier.

Step 3: Amplifier:

Amplifiers have their own rating. And each amplifier is suited for a particular set of speakers.

First, check the output ratings of the amplifier that you want to buy. If it matches the rating of the speaker, then great! or else search for another one (the internet has tons of options).

The important thing to keep in mind is that the output wattage of the amplifier should ALWAYS be lower than or equal to the speaker wattage. Or else it will definitely damage the speaker. Also, the impedance of the speakers and the amplifier should match. The speaker impedance should be higher than the amplifier impedance.

Step 4: Connecting Speaker, Audio Amplifier and Bluetooth Module:

I'm using a 5W 4ohms speaker and PAM8406 (2 x 5W) audio amplifier. But for any type of speaker or amplifier, the connections remain the same.

You can choose an amplifier with either two channels or one channel. But I suggest you choose two mono channeled amplifiers. Because I used a dual channel amplifier and there were a lot of distortions.

Step 5: Audio Jack ( Additional ) :

A male audio jack has three terminals, ground, left signal, and right signal. The Bluetooth module has 4 important pinouts: 5V, ground, left, and right. The female audio jack in the Bluetooth module has the left, right and the ground connected. So we can use this to connect the amplifier and the Bluetooth audio module using the male audio jack. I used this for easy connect or disconnect. Instead of this, you can solder each wire to the appropriate terminals.

I've used the above Bluetooth audio receiver module. So, we can simply just connect the audio jack to make the connections for left, right and ground. But we have to power this module with a 5V supply.

In other Bluetooth modules, there might be a pinout for all the connections and so you can simply connect those using jumper wires.

Courtesy of Images: Google

Step 6: Connecting Power Supply (USB):

From a female USB connector, we get a 5V supply. We can use this to supply power to the Bluetooth module and the amplifier. So, just solder them using wires from the 5V line of USB to amplifier and Bluetooth module and have a common ground line.

After this, if we connect it using a male to male USB wire from laptop to the female USB connector, the whole setup should power up. If not check the connections again.

Images: Google

Step 7: Connecting Power Supply (portable):

Instead of powering the speaker through USB we can power it up using 18650 Li-Ion batteries.

One thing to keep in mind is that Li-Ion gives us 3.7V so, we need to boost this to the required 5V. For this, we will use a DC-DC boost converter.

Connect the positive terminal of the battery to VIN+ and negative terminal of the battery to VIN-. After this turn the screw in the DC-DC booster to 5V using a multimeter. From VOUT we can take the 5V line to supply power to the amplifier and the Bluetooth module.

What will happen after the after the battery is depleted? For this, we make another circuit using TP4056 (Battery charger module). I've put up the connection above in the picture. We can charge the battery using a micro USB cable.

Courtesy: Google Images

Step 8: Result:

So, finally, if everything goes right you should be able to connect to the Bluetooth audio module and play songs.

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2 Discussions

No! The speaker impedance must be the same of the impedance of the amplifier. An impedance greater than the one of the amplifier is tolerate; an impedance lower than the one of the amplifier it is dangerous for the amplifier. But, if the power source is a small battery you cannot destroy the amplifier neither the speakers.Anyway your idea it's a good idea.